RB25 SAFC Random Richness

[FinkenS14]

Hey guys I got a issue (kinda) with my RB25 and its not really bothering me, just making me wonder.

Its a bone stock 25, stock turbo at 12psi, FMIC, Yamamoto tuned ECU (came with the motor set), and Im tuning it with an SAFC.

Since I live in Colorado, and the air is much thinner, and it was a tuned ECU, even at 12psi on the stock tune, no SAFC my AFR's were 9.9-10.2 at wide open.

So I got an SAFC2 to fix the problem.

I got a good base tune on it, 11.5 AFR's at wide open using my Innovate wideband. And it hauled wonderfully. Much better driveability around town aswell.

Well every now and then, my car will go rich again. From the SAFC tuned 11.5 to about 10.8, and the car feels a little sluggish.

No SAFC wires are loose, they are all soldered and heat shrinked, I converted the harness on my own, from what I know no breaks in the wiring, everything is soldered and heat shrinked.

What could be the issue?

One of my buddies said its the SAFC causing my issues and that since the ECU isnt reading air temp anymore, or something along those lines, the cars AFR's will change on a day to day basis.

I have kinda noticed this.

On cold night the car will be perfect, 11.5-11.8, no knock, pulls smooth and strong.

But on hotter days it richens up and has the sluggish issue.

Any thoughts?

[Infinitiguy19]

Any Check Engine Light codes when this happens?

Compare sensor readings when idling fines and compare to rough idle.

[gomer23]

I had a SAFC2 on my RB for a couple months at one point and it was the biggest waste of time trying to tune with. Now I was running a stock ECU but the problem I had was I had to "take" so much fuel out with the SAFC the ECU would compensate the drastic change by changing the timing around on me and thus undoing all the tuning I had just done. There have been a few others on here that have run into the same problem. I am not saying this is your problem for sure but from my experience and research the SAFC2 and the RB ECU don't play nice with each other.

[Xit40]

I'm not exactly sure how the SAFC hooks up in an RB so I can't comment on the air temp thing, but I do have experience with them. What kind of temp. differences are you talking about? 20 degrees? 40 degrees? How much fuel (the SAFC is actually reducing the MAF signal before it gets to the ECU, which in turn reduces fuel) are you pulling out? It could just be due to reduced O2 density at increased temperatures (especially since you're already at increased altitude, double whammy). Turbo cars are very finicky about temperature changes. Piggyback systems like the SAFC are kinda a pain in the butt to tune with. They can cause issues such as what you're describing depending on how much fuel you're pulling out (or well MAF signal). I used to have one on my DSM it kinda sucked if you were making larger adjustments (anything over 18-20%) and occasionally made the car due strange things.

[FinkenS14]

Im taking out about 15-18% fuel to keep it right around 11.8-12.0 afrs.

Temp changes are around the 20-30 degree range.

Im done screwing with the ting, and I got a Power FC with a Lightning MAF and pop charger from Kim Wolf.